Price is per set. Part of the rear brake system, which uses brake shoes that expand outward and press against the inside surface of the brake drum to slow down the wheel. Weight: Approximately 16.60 Pounds. Genuine BMW parts are built to BMW's quality standards for proper fitment, performance, and longevity. Brake drums are wear items that require regular inspection and servicing. You can check for wear or damage to the brake drum by tapping it with a spanner or using a dial gauge to check for out-of-roundness.